ESP stuff is very cheap and works well, but the Arduino Uno is a great board/ecosystem for beginners and simple projects. Being 5V is more convenient for a lot of things, and having the pin headers already on the board that you can just start plugging things in with jumper wires is great.

The Arduino IDE is awesome for an extremely quick setup time. You can very easily download libraries and add them to your project, you don't have to create a blank source file, you just have to fill in setup() and loop(). The Arduino IDE makes it very easy to set up a new board and download code to it.

Much of this also applies to the Arduino IDE with and ESP32, but what I really appreciate about the whole Arduino ecosystem is if you want to do something really simple, like say, activate a servo when some sensor reaches a certain value, you literally only have to type 5-6 lines of code. You're not messing around with SDKs and Makefiles and git cloning repositories etc etc etc. You can get kits for $70 that have an Arduino clone, and a bunch of different sensors, servos, steppers, etc. It's absolutely fantastic for teaching basic programming and electronics.